Same old backstory - truck (22RE) doesn't like to start when it's cold (below 50deg). Yes - I've done a lot of searching, and consulted the service manual. The cold start time switch tests within spec, and the cold start injector fires when given direct power/ground from the battery.

My main question here regards the power that's getting to the cold start injector itself. On cranking, the black wire for the injector receives 9.75V, and the green wire receives 4V which creeps up to 9V over the course of 1-2 seconds. (I've already run RAD4Runner's ignition switch bypass wire, but I'm still only getting the listed voltage.)

Should both wires be receiving battery voltage, or should one show ground continuity? I tested the continuity from the time switch plug to the injector plug, and they are not shorted to each other.

If both wires are supposed to be receiving voltage, then should I assume this is a ground issue?

TIA, as always!

 

As an update to my own issue -

I disconnected the CSI plug, and jumped the power wire to the injector, and then grounded the other post on the CSI to the ground directly. After doing this, the truck started right up!

This to me means that there is a short somewhere downstream of the CSI plug, which is putting power to both posts on the CSI, rather than just one. I'll further update, in the hopes that this will help someone down the line as well.

 

Assuming stock circuit:


When cranking. Black wire of CSI should get close to 12 Volts. You are getting 9 volts because of normal voltage drop from starter drawing a lot of current from battery, AND from resistances in the wiring.
When hot, CSI timer switch opens, Green wire of CSI (STJ of CSI timer switch) should have close to 12V. This is "leakage" through coil of CSI.
When cold, CSI timer switch closes, Green wire of CSI (STJ of CSI timer switch) is connected to ground so it should read close to Zero volt.

"4V which creeps up to 9V over the course of 1-2 seconds"
"creeps up to 9V over the course of 1-2 seconds" suggests that the CSI timer switch is closing, and after a couple of seconds opens, which is normal to prevent the CSI from overheating or from putting out too much fuel.
"4V" suggests that the CSI timer switch is not closing all the way / working right, OR is not getting enough ground through its mounting thread. Mounting thread on CSI timer switch should have good connection to ground. I suggest you clean it with battery terminal brush.




How Cold Start Injector System Works Here: https://www.yotatech.com/forums/f116.../#post52385373

 

Thanks for the explanations @RAD4Runner - I’ll give the above a shot!